In oil or fuel filters, it is common to utilize a casing in which a filter element is positioned. The casing has an integral closed end and the other end sealed by a closure member. A spring normally urges the filter element in one direction against the closure member.
In such oil filter constructions, a separate spring is most commonly used. Although it has heretofore been suggested that the spring be made a part of the end member of the cartridge, as in U.S. Pat. Nos. 3,258,122 and 3,567,023, no practical construction has been found commercially to eliminate the use of the separate spring.
Accordingly, among the objects of the invention are to provide a filter wherein the spring force for holding the cartridge in position is obtained by integral spring members forming a part of the end element of the cartridge; wherein such a construction is achieved most economically without waste; wherein the spring force is obtained during the assembly of the filter; and wherein a novel method is utilized in making the filter.